Field of the Disclosure
The invention relates to blood separation systems and methods. More particularly, the invention relates to blood separation systems and methods also involving leukoreduction of the blood or of a separated cellular blood component.
Description of Related Art
Traditional blood collection continues to rely heavily on manual collection of whole blood from healthy donors through blood drives, from donor visits to blood centers or hospitals and the like. In typical manual collection, whole blood is collected by simply flowing it, under the force of gravity and venous pressure, from the vein of the donor into a collection container. The amount of whole blood drawn is typically a “unit,” which is about 450 ml.
More specifically, such a collection typically employs a pre-assembled arrangement of tubing and containers or bags, including a flexible plastic primary container or bag for receiving a unit of whole blood from a donor and one or more “satellite” containers or bags. The blood is first collected in the primary container, which also contains an anticoagulant (typically, but not exclusively, containing sodium citrate, phosphate, and dextrose—often referred to as CPD). A preservative (often called an “additive solution” or AS, and commonly containing a saline, adenine, and glucose medium—which is referred to as SAG) may be included as part of a larger assembly of bags and tubes that are used in processing after the blood is collected.
After collection of a unit of whole blood, it is common practice in blood banking to transport the unit of whole blood, with connected tubing and containers, to a blood component processing laboratory, commonly referred to as a “back lab,” for further processing. Further processing usually entails manually loading the primary container and associated tubing and satellite containers into a centrifuge to separate the whole blood into components such as concentrated red cells and platelet-rich or platelet-poor plasma. These components are then manually expressed from the primary container into other pre-connected satellite containers, and may be again centrifuged to separate the platelets from plasma. Subsequently, the blood components may be leukoreduced (i.e., have the white blood cells or leukocytes contained therein removed) by filtration for further processing or storage. In short, this process is time consuming, labor intensive, and subject to possible human error.
While many of the prior blood separation apparatus and procedures have employed centrifugal separation principles, there is another class of devices that employs relatively rotating surfaces, at least one of which carries a porous membrane. Typically the device employs an outer stationary housing and an internal spinning rotor covered by a porous membrane. Detailed descriptions of membrane separators may be found in U.S. Pat. Nos. 5,194,145; 4,776,964; 4,753,729; and 5,135,667, all of which are incorporated by reference herein.
Such systems may include a membrane-covered spinner having an interior collection system disposed within a stationary shell or housing. Alternatively, an inner surface of the stationary housing may be covered by a membrane, or both the spinner and the housing may include associated membranes. For purposes of this description, these will be referred to as membrane separators. In such membrane separators, blood is fed into an annular space or gap between the spinner and the shell and moves along the longitudinal axis of the shell toward an exit region. Plasma passes through the membrane and exits through an outlet port, while the remaining cellular blood components (red blood cells, platelets, and white cells) remain in the gap and move to the exit region between the spinner and the shell. Membrane separators have been found to provide excellent plasma filtration rates, due primarily to the unique flow patterns (“Taylor vortices”) induced in the gap between the spinning membrane and the shell. The Taylor vortices help to keep the blood cells from depositing on and fouling or clogging the membrane.
While membrane separators have been widely used for the collection of plasma, they have not typically been used for the collection of other blood components, specifically red blood cells. One example of a membrane separator used in the collection of separated red blood cells is described in PCT Patent Application Publication No. WO 2014/039086 A1, which is incorporated by reference in its entirety.
The subject matter disclosed herein provides further advances in membrane separators, particularly in terms of the reduction of leukocytes in a final collected cellular blood component.